Manufacture of artificial materials



e for the production of particular kinds of fabrics,

Patented Jan. 3, 1939 guano MANUFACTURE or ARTIFICIAL Mimmms Henry Dreyfus, London, and Robert Wighton Moncriefi and Frank Brentnall Hill, Spondon, near Derby, England, assignors to Celanese Corporation of America, a corporation of Delaware No Drawing. Application November 19, 1936, Se-

rial No. 111,596. In Great Britain February 2,

5 Claims. (Cl. 1172) The cellulose derivative artificial yarns which are employed commercially for the production of normal plain fabrics have, in general, a twist of about 2 to 5 turns per inch, while yarns having somewhat higher twist, for example 10 to 15 up to about 20 turns per inch, may be employed for example voile fabrics. It has now been discovered that artificial yarns may be stretched in the presence of hot aqueous fluid, which may be steam'or hot water, e. g., by 15-40 or 50% up to 100% or more of their original length, and twisted in a single operation, and yarns .of relatively low twist (i. e., up to about 20 turns per inch) and of increased tenacity may be obtained. The filaments twisted according to the present invention may have been obtained from cellulose derivative' solutions, or have been produced by a process of esteriflcation or etherification without loss of structure, e. g. by continuous filaments of regenerated cellulose in the presence of benzene or other suitable nonsolvent. They may contain delustring or loading agents, e. g., barium sulphate, titanium dioxide, stannic phosphate or diacetyl benzidine, and may have been subjected to stretching and/or shrinking operations, e. g. as described in U. S. applications S. Nos. 4,510 filed February 1, 1935, 4,511 filed February 1, 1935 and 611,240 filed May 13, 1932. Again, the fiiaments'may be saponified, e. g., partially saponified throughout their crosssection or superficially saponified.

The steam employed in the process of the present invention may be saturated or wet steam and may beat temperatures of the order of to C. or -C., e. g. at a temperature corresponding to a super-atmospheric pressure of 1 to 5 or 10 cm. of water, or at higher temperatures, for example C. or up to C. or more, corresponding to pressures of 10, 15 or 20 up to 30 pounds per square inch or more above atmospheric pressure.

The combined stretching and twisting operation may be efiected by means of the apparatus described in British specification No. 440,653,

wherein the steaming chamber for the yarn consists of a short tube offset from a main steam acetylation of '12 to 14 turns per inch A method of carrying out the process of the present invention which has been found particularly valuable consists in drawing a yarn having no twist or only a very low twist, for. example 0.5 or 1 turn per inch, from'a bobbin which is rotating at a high speed, for example 3000, 5000, 11,000,.18,000 or more revolutions per minute, through a substantially closed steam chamber and then taking it up on a bobbin rotating at a suitablespeed, which will depend inter alia on the speed of rotation of the supply bobbin and on the number of turns per inch which it is desired to insert in the yarn. In this process a tension is exerted on the yarn which, on account of the action of the steam on the yarn, stretches it to a degree which will depend upon the steaming conditions. In general ,the higher the temperature of the steam the greater will be the stretch produced. For example by drawing a cellulose acetate yarn of about denier from a supply bobbin rotating at 11,000 revolutions per minute into and out of a steaming chamber of about 3 inches in length and taking it up at a speed of about 140 metres perminute' a stretch corresponding to a reduction in denier of from 150 to about 130 may be produced with wet steam at a pressure. of about 10 pounds gauge,

while with wet steam at a pressure of about 30 pounds gauge the denier may be reduced to about 100-110. -By this means a yarn of increased tenacity having a twist of about 2 turns per inch may be obtained.

Higher degrees of twist may be inserted. For example cellulose acetate yarn having a twist of and a considerably increased tenacity may be obtained by means of an apparatus similar to that illustrated in British specification No. 440,653, using 9-inch tubes offset from a main steam pipe and containing wet steam at a. pressure of about 5-10 pounds per square inch above atmospheric pressure, the spindle speeds being 6000-7000 revolutions per minute.

best results will depend inter alia upon the takeup speed of the yarn and may, e. g., be 3 inches or 6 inches up to 18 inches .or more. it appears that the gre'aterthe take-up speed the longer should be the path of the yarn through the steam, provided that the other conditions remain the same. For example, while, using a supp bobbin rotating at about 5000 revolutions per minute, good results may be obtained with a 3 inch steam chamber at a pressure of 30 pounds perinch and a take-up speed of about 60 metresv found that better results are, 55

per minute, it is In general trap STATES PATENT OFFICE The length of the steam chamber yielding the results.

Another method of carrying out the process of the present invention consists in feeding yarn from a dry spinning apparatus, a bobbin or other source, through a steaming chamber and taking it up on a winding and twisting device, e. g., a

ring or cap spinning apparatus.

produced according to the process of the present invention, the tension may be increased, e. g. by inserting a gate or similarly acting device in the If it is desired to increase the degree of stretch path of the yarn. Thus a bundle of filaments maybe drawn from a rapidly rotating bobbin through a floating ring device as described in U. S. Patent No. 1,784,581, then through a steam chamber and finally taken up on a bobbin or the like.

The process of the present invention may also be carried out using. hot water instead of steam. For example the yarn may be drawn ofl from a rotating bobbin and passed upwards through a small hole in a suitable receptacle containing hot water, and thence to a winding device. The

hole may be provided with means adapted to lead away any liquid issuing from the hole and prevent it from reaching the rotating bobbin. If desired the hole may take the form of a tube of fine bore fixed in the receptacle whereby the flow of liquid at the entrance of the thread may be. reduced. Again, hot water may be supplied to the yarn by passing it in contact with a horizontal roller, preferably circumferentially grooved, arranged to rotate in a bath or hot water and so carry water to the thread. Water may be used at temperatures of 95 or 100 C. or at temperatures considerably higher, as for example 110-130 or 140 C. or more. At temperatures above the boiling point the water is employed under pressure in a substantially closed chamber, and even when working at the boiling point or at temperatures below the boiling point it is preferable to use such a chamber.

Yarns made oi cellulose acetate or other oranic ester of cellulose which have been twisted and stretched according to the process of the present invention may bepartially or completely saponified, for example with caustic soda or other inorganic base, or with organic bases, for example methylamine or ethylene diamine, as described in U. S. applications S. Nos. 329 filed January 4, 1935, 752,376 filed November 9, 1934 and 756,285 filed December 6, 1934. Organic bases, and inorganic bases such as-sodium silicate, are particularly useful when it is desired to eil'ect deep-seated saponification.

The process of the present invention is of particular-value in the stretching and twisting of artificial filaments having a basis of cellulose acetate and especially cellulose. acetate having an acetyl value oi. about 52 to 66%. It may, however, also be employed in the stretching and twisting of other artificial filaments, for example continuous filaments having a basis or organic esters of cellulose other than cellulose acetate, such as cellulose iormate, cellulose propionate, cellulose butyrate and cellulose nitro-acetate, cellulose ethers, for example methyl, ethyl and butyl celluloses, and cellulose ether-esters, for example ethyl cellulose acetate and oxy-ethyl cellulose acetate, and filaments having a basis of regenerated cellulose.

Having described our invention what we desire to secure by Letters Patent is:

1. Process for the production of low twist yarn of improved tenacity, which comprises stretching a yarn having a basis of an organic derivative of cellulose by at least 40% of its original length by passing .it through hot aqueous fluid at a temperature 01' at least C. during its travel between feed and take-up devices which insert a low twist in the yarn, the stretching and twisting of the yarn being effected in the presence of the hot aqueous fluid. g

2. Process for the production of low twist yarn of improved tenacity, which comprises stretching a yarn having a basis of an organic derivative of cellulose by at least 40% of its original length by passing it through hot water at a temperature of at least 95' C. during its travel between feed and take-up devices which insert alow twist in the yarn, the stretching and twisting of the yarn beng effected in the actual presence of the hot water.

3. Process for the production 01' low twist yarn of improved tenacity, which comprises stretching a yarn having a basis of an organic derivative oi cellulose by at least 40% of its original length by passing it through wet steam at a temperature of at least 95 C. during its travel between teed and take up devices which insert a low twist in the yarn, the stretching and twisting of the yarn being effected in the actual presence of the wet steam.

4. Process for the production of low twist yarn of improved tenacity, which comprises stretching a yarn having a basis of cellulose acetate by at least 40% 01' its original length by passing it through wet steam at a temperature of at least C. during its travel between feed and take-up devices which insert a low twist in the yarn, the stretching and twisting of the yarn being affected in the actual presence 01' the wet steam.

5. Process for the production of low twist yarn of improved tenacity, which comprises stretching a yarn having a basis 0'! cellulose acetate by at least 40% of its original length by passing it through hot water at a temperature of at least 120 C. during its travel between feed and take- .up devices which insert a low twist in the yarn,

the stretching and twisting of the yarn being efiected in the actual presence oi. the hot water.

HENRY DREYFUS.

ROBERT WIGHTON MONCRIEFF. FRANK BRENTNALL HILL. 

